Pickproof lock



Nov. 22, 1938. J, J, OCQNNELL 2,137,504

PIGKPRooF Loox Filed Jun 12, 1957 l INVENTR A ,Jahn OConnel] TTORNEY5Patented Nov. 22, 1938 UNITED STATES PATENT OFFICE 4 Claims.

The present invention relates to cylinder locks and more particularly'tocylinder locks wherein auxiliary means are provided for making the lockpick-proof.

An object of the present invention is a lock wherein auxiliary plungersare provided for securing the key plug against rotation 'and theauxiliary plungers carry means for securing them when in lockingposition. Another object is a lock of this type wherein the auxiliaryplungers may be readily reset to released position. A further object isa lock of this type which may be made in very small sizes. These andother objects Will be readily understood from the following descriptionwith reference to the accompanying drawing, in which:

Fig. 1 is a sectional view of the preferred embodiment of the inventionon the line I-I of Fig. 2;

Fig. 2 is a sectional view taken on the line 2-2 of Fig. 1;

Fig. 3 is a fragmentary view of one auxiliary plunger of Fig. 1 inlocking position;

Fig. 4 is a view of another embodiment of the invention on the line 4-4of Fig. 5;

Fig. 5 is a sectional view on the line 5-5 of Fig. 4; and

Fig. 6 is a. top view of the plungers of Fig. 4.

Referring to the drawing, the lock comprises the usual barrel orcylinder 2, the key plug 4 having a keyway 6 therein, pin tumblers 8,drivers I0, driver springs I2, and cylinder slide I4. The drivers IIJand pin tumblers 8 being so related that upon the insertion of theproper key the upper end of the pin tumblers 8 and lower end of thedrivers I0 are alined with the periphery of the key plug 6 wherebyturning of the key will rotate same. All the foregoing structure iscommon to locks of this type.

In accordance with the present invention there is provided (Fig. 1) aset of auxiliary plungers I6 arranged at an angle to the drivers I0 andcarried in bores II of cylinder 2 and adapted to coact with pin tumblers8 to lock the key plug should the lock be picked or an unauthorized keyemployed. Each plunger is provided with a double head, the top head I8having a smaller diameter than the lower head 20, this constructionallowing a split resilient ring 22 to be carried in the recess 2lbetween the heads. The bore is formed with a shoulder 25 on which restsa positioning and stop member 24 having an inside diameter approximatelythat of the top head I8 and an outside diameter greater than the lowerhead 2D, the lower end of the position- (Cl. 'l0-364) ing member alsoforming al stop 21. A spring 28 normally biases the plunger downward,the spring being held between head I8 and slide 30. With theconstruction shown the ring 22 may be set in recess 2| between heads I8and 20 and held by positioning member 24, the entire assembly may thenbe inserted in the barrel 2, spring'. 28 and slide 30 then beingpositioned, whereupon the plunger will be positioned as shown in Figs. 1l and 2. If the key plug 4. is turned without the proper key, plunger I6will coact with one of the pin turnblers 8 whereupon spring ring 22 willexpand beneath stop 2'I and lock the plunger in place as shown in Fig.3. To reset it is only necessary to remove slide 30, drop out the partsand reassemble. This construction is particularly adaptable to verysmall locks such as those used in automobiles, and although only twoplungers I6 have been shown it is apparent that one could be associatedwith each tumbler.

In the embodiment shown in Fig. 4 the auX- iliary plungers 32 areprovided with an enlarged head 34 which, as shown, may be square orprovided with any suitable means to make it nonrotatable. The auxiliaryplungersI are biased by springs 3B and held in position by the usualsocket closure 38. Each auxiliary plunger 32 is provided with a stop pin40 which is biased against the wall of the barrel by a spring 42.Arranged at right angles to the plungers and alined with the stop pins40 is an opening 44 one end of which is closed with a cap screw 4S. Thusif the auxiliary locking plunger moves to engage the key plug shouldsame be turned without the proper key, the stop pin 40 will enteropening 44 and be limited in its movement by cap screw 46 and thus lockplunger 32 against movement. In like manner plunger 48 will be lockedagainst movement by stop pin 43, which will enter opening 44 and abuthead 34 of plunger 32. With this construction it is possible to resetthe auxiliary plunger by removing closure 38, and then by removing capscrew 46 the stop pin 40 may be pushed back into plunger head 34 by anysuitable wire and then raised into position, whereupon the next stop pin40 may be repressed and the next auxiliary plunger reset. It is alsopossible to simply remove plug 46, push back the stop pin 40, and thenraise the plunger by using any suitable picking tool.

As in the rst embodiment the auxiliary plungers and stop pins areassembled and then inserted in the sockets in a single operation.Although only two auxiliary plungers have been shown and their size hasbeen enlarged for purposes of clear illustration, it is evident that oneauxiliary plunger could be associated With each key plug tumbler I2.

As many changes could be made in the above construction and manyapparently Widely different embodiments of this invention could be madeWithout departing from the scope thereof, it is intended that all mattercontained in the above description or shown in the accompanying drawingshall be interpreted as illustrative and not in a limiting sense.

The following is claimed:

l. A lock comprising a cylinder, a key plug rotatably mounted in thecylinder, a plurality of pin tumblers carried by the plug, a pluralityof drivers carried by the cylinder and alinable With the pin tumblers inone position, a plurality of auxiliary plungers carried by the cylinderand alinable with the pin tumblers when the key plug is rotated from thefirst position, stop means carried by the auxiliary plungers and adaptedto hold the same against movement when in engagement With the pintumblers, and resilient means for operating said stop means.

2. A look comprising a cylinder, a key plug rotatably mounted in thecylinder, a plurality of pin tumblers carried by the plug, a pluralityof drivers carried by the cylinder and alinable With the pin tumblers inone position, a plurality of auxiliary .plungers carried by the cylinderand alinable With the pin tumblers when the key plug is rotated from thefirst position, a resilient member carried by the plunger, means formaintaining the member in compressed position when the plunger is out ofalinement with the pin tumblers and for allowing the same to expand whenin alinement with the pin tumblers.

3. A lock comprising a cylinder, a key plug rotatably mounted in thecylinder, a plurality of pin tumblers carried by the key plug, aplurality of drivers carried by the cylinder `and alinable` with the pintumblers in one position, a plurality of auxiliary plungers carried bythe cylinder and alinable With the pin tumblers when rotated from thefirst position, said plungers having a double head and a recess betweenthe heads, a resilient split ring carried in the recess, a positioningmember adapted to t around the top head and hold said ring undercompression when said plungers are out of alinement With the pintumblers, said positioning member having a down- Wardly facing shoulderbeneath which said ring Will expand when said plungers are in alinementWith the pin tumblers.

4. A lock comprising a cylinder, a key plug rotatably mounted in thecylinder, a plurality of pin tumblers carried by the key plug andalinable with the pin tumblers in one position, a plurality ofnon-rotatable auxiliary plungers carried by the cylinder and alinableWith the pin tumblers When the key plug is rotated from the firstposition, said cylinder having an opening therein at right angles to theplungers, a stop` member carried by said plungers and adapted to entersaid opening when the plungers aline with the pin tumblers, andresilient means for operating said stop member.

JOHN J. OCONNELL.

